备份与恢复系列 六 续 日志挖掘（Log Miner）找回update语句

在上一篇的试验中使用logminer可以很容易的找到误删除的表，下面来看一个关于update的例子。


1.创建一个数据字典
EXECUTE dbms_logmnr_d.build( -
        dictionary_filename => 'dictionary.ora', -
        dictionary_location => '/home/oracle');


2.产生update语句
conn scott/tiger
update emp set sal=10,comm=20 where empno=7844;
commit;


3，为分析制定日志文件
conn / as sysdba
select member from v$logfile where group#=(select group# from v$log where status='CURRENT');


EXECUTE dbms_logmnr.add_logfile( -
        logfilename => '/oradata/PRACTICE/redo03.log', -
        options => dbms_logmnr.NEW);


查看将要分析的日志
select DB_NAME,THREAD_SQN,FILENAME from v$logmnr_logs;


DB_NAME                  THREAD_SQN FILENAME
------------------------ ---------- -----------------------------------------
PRACTICE                         24 /oradata/PRACTICE/redo03.log


4，启动log miner
conn / as sysdba
EXECUTE dbms_logmnr.start_logmnr( -
        dictfilename => '/home/oracle/dictionary.ora');


查看统计信息，没有挖掘出任何数据
SELECT sql_redo,sql_undo
from v$logmnr_contents
where seg_name='EMP'
and seg_owner='SCOTT'
and seg_type_name='TABLE';


no rows selected




接下来有请今天的主角supplemental log


1，增加supplemental log
conn / as sysdba
alter database add supplemental log data;


SELECT supplemental_log_data_min FROM v$database;


SUPPLEMENTAL_LOG_DATA_MI
------------------------
YES


2，产生update语句
conn scott/tiger
SCOTT@PRACTICE >update emp set sal=10,comm=20 where empno=7844;


commit;


3,为分析制定日志文件
select member from v$logfile where group#=(select group# from v$log where status='CURRENT');


MEMBER
--------------------------------------------------------------------------------
/oradata/PRACTICE/redo03.log




SYS@PRACTICE >EXECUTE dbms_logmnr.add_logfile( -
>         logfilename => '/oradata/PRACTICE/redo03.log', -
>         options => dbms_logmnr.NEW);




SYS@PRACTICE >select DB_NAME,THREAD_SQN,FILENAME from v$logmnr_logs;


DB_NAME                  THREAD_SQN
------------------------ ----------
FILENAME
--------------------------------------------------------------------------------
PRACTICE                         24
/oradata/PRACTICE/redo03.log


4,启动log miner
SYS@PRACTICE >EXECUTE dbms_logmnr.start_logmnr( -
>         dictfilename => '/home/oracle/dictionary.ora');


PL/SQL procedure successfully completed.




SYS@PRACTICE >SELECT sql_redo,sql_undo
  2  from v$logmnr_contents
  3  where seg_name='EMP'
  4  and seg_owner='SCOTT'
  5  and seg_type_name='TABLE';


SQL_REDO
--------------------------------------------------------------------------------
SQL_UNDO
--------------------------------------------------------------------------------
update "SCOTT"."EMP" set "SAL" = '10', "COMM" = '20' where "SAL" = '100' and "CO
MM" = '200' and ROWID = 'AAASZHAAEAAAACXAAJ';
update "SCOTT"."EMP" set "SAL" = '100', "COMM" = '200' where "SAL" = '10' and "C
OMM" = '20' and ROWID = 'AAASZHAAEAAAACXAAJ';


实验成功，挖掘到了update语句。


关闭日志挖掘
execute dbms_logmnr.end_logmnr;


删除supplemental log
alter database drop supplemental log data;